Bought it - went to the trouble of setting up a couple of campaigns for my woocommerce store.
There referral codes just send new visitors to the same referral sign up page. Not to go shopping and get the discount.
Tried to seek support but their emails bounced to mat@, hello@ and hi@
Seems to be broken and basically dead.

Had to refund as it fundamentally doesn't do what it is supposed to, with no support.